LAUSR

Abstract Silicon nitride (Si 3 N 4 ) bioceramics with standard sintering additives (Al 2 O 3 and Y 2 O 3 ) are used in spinal fusion. Alternative Si 3 N 4 bioceramics with biologically beneficial sintering additives could lead to improved osseointegrative properties. The aim of this study is to obtain dense and strong Si 3 N 4 bioceramics by using SrO, MgO and SiO 2 as sintering additives, and evaluate the effect of these sintering additives on microstructures and properties of Si 3 N 4 bioceramics. Raw powders with 10 wt% and 18 wt% sintering additives were sintered by spark plasma sintering. Samples sintered at 1750 °C, with an applied pressure of 60 MPa and a holding time of 3 min, showed the highest content of β-Si 3 N 4 (94.9%). The mechanical properties of the developed Si 3 N 4 bioceramics are comparable to the mechanical properties of currently used structural Si 3 N 4 ceramics sintered with standard sintering additives (Al 2 O 3 and Y 2 O 3 ). The highest flexural strength of the developed Si 3 N 4 bioceramics reached 1079 MPa. Ion release results showed that Sr 2+ , Mg 2+ and Si 4+ ions kept leaching out within 10 days’ immersion. The degradable Si 3 N 4 bioceramics with adequate strength and biologically beneficial sintering additives show the promise for load bearing biomedical applications, such as spinal fusion.